Fernandes-Silva, M. (Marcela)

Filtering

2013 - 20152

Settings

Author search.filters.isAuthorOfPublication.b21571b6-ef77-4a45-bf00-220fd48d36db

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Study of thermal degradation of PLGA, PLGA nanospheres and PLGA/Maghemite superparamagnetic nanospheres
    (ABM; ABC; ABPol, 2015) Aparicio-de-Oliveira, A.J. (Adilson Jesús); Fernandes-Silva, M. (Marcela); Gomez-Pineda, E.A. (Edgardo Alfonso); Winkler-Hechenleitner, A.A. (Ana Adelina); Irache, J.M. (Juan Manuel)
    Poly(glycolide-co-lactide) (PLGA) nanospheres containing magnetic materials have been extensively studied because of its biomedical applications. Therefore, it is very important to know thermal properties of these materials in addition to other physical properties. Thermal degradation activation energy (Eα) of PLGA nanospheres with maghemite entrapment (PLGA-Mag), PLGA nanospheres (hollow spheres) (PLGA-H) obtained by an emulsion method and unprocessed PLGA (PLGA-R) were calculated by isoconversional Vyazovkin method based on data of TG analysis in order to evaluate modifications in thermal behavior caused by nanospheres obtainment process or by maghemite entrapment. Both hydrodynamic diameter in the range of 200-250 nm and polydispersity index lower than 0.3 are considered satisfactory. Thermal degradation of PLGA-R begins at higher temperatures than those of PLGA-H and PLGA-Mag, but processed samples presented increase in thermal stability, which was greater before processing by emulsion and in the presence of the magnetic materials. PLGA-Mag presents superparamagnetic behavior at room temperature.
  • Thumbnail Image
    Optimization of maghemite-loaded PLGA nanospheres for biomedical applications
    (Elsevier, 2013) Fernandes-Silva, M. (Marcela); Agüeros, M. (Maite); Gomez-Pineda, E.A. (Edgardo Alfonso); Winkler-Hechenleitner, A.A. (Ana Adelina); Peñalva, R. (Rebeca); Irache, J.M. (Juan Manuel); Oliveira, D.M.F. (Daniela M.F.) de
    Magnetic nanoparticles have been proposed as interesting tools for biomedical purposes. One of their promising utilization is the MRI in which magnetic substances like maghemite are used in a nanometric size and encapsulated within locally biodegradable nanoparticles. In this work, maghemite has been obtained by a modified sol-gel method and encapsulated in polymer-based nanospheres. The nanospheres have been prepared by single emulsion evaporation method. The different parameters influencing the size, polydispersity index and zeta potential surface of nanospheres were investigated. The size of nanospheres was found to increase as the concentration of PLGA increases, but lower sizes were obtained for 3 min of sonication time and surfactant concentration of 1%. Zeta potential response of magnetic nanospheres towards pH variation was similar to that of maghemite-free nanospheres confirming the encapsulation of maghemite within PLGA nanospheres. The maghemite entrapment efficiency and maghemite content for nanospheres are 12% and 0.59% w/w respectively.